Technologies for large scale purification of monoclonal antibodies are becoming increasingly important for new therapies. Affinity chromatography is effective, but expense and low throughput complicate large scale operation. Membrane chromatography provides higher throughput, and would be an excellent option if the capacity, selectivity, and pore size distribution can be improved. The focus of this proposal is to meet each of these challenges using functionalized membranes. Functionalized membranes provide excellent throughput and high capacity because adsorption sites are located on polymer grafts in the pores, rather than on the pore surface. In the proposed research, the adsorption sites are based on an analog for the phenylalanine-132/tyrosine-133 motif, incorporated multiple times along each functionalized chain in a polymer brush immobilized in the pores of a microfiltration membrane. The polymer brush is formed by sequential cationic polymerization of a series of substituted styrenes. Glycine functionalization of chloromethyl styrene repeat units will provide spacers to limit steric hindrance and inhibit denaturing of the adsorbed antibody. Individual and competitive sorption of bovine immunoglobulin and bovine serum albumin will be used as a test system for capacity and selectivity. The functionalized polymer brushes will be extracted and fully characterized ex-situ by 1H NMR and X-ray crystallography. In addition, functionalized membranes will be tested for pore size distribution to characterize narrowing of the pore size. This research will result in improved membrane adsorbers for protein and antibody separation. In addition, it will lead to discoveries in sequential polymerization to generate customized structures, sequencing of non-peptide polymers, and design of synthetic affinity ligands. The results of this research will be broadly disseminated in refereed journal publications and in presentations at regional and national meetings.
